This invention relates to a method and apparatus for remote imaging of oceanographic artifacts at depths down to and below the thermocline, for example, internal waves that exist at various depths in the ocean, particularly around the thermocline. More particularly, the invention relates to a technique for detecting and identifying internal waves using an imaging lidar system.
For a number of years, oceanographers have been studying internal waves, and measuring their behavior. These techniques are limited because of the need to insert sensors directly in the ocean to a given depth and in a given location to obtain data. What these sensors actually record is the presence of internal waves passing a given geographic point. Simple bathymetric techniques cannot provide a physical picture of the wave but only, with great difficulty, infer its presence. The differential colorimetric effects of vertical displacement on upwelling light from layers of biologically active material in the thermocline has been studied. These changes in the spectrum of upwelling light can also be detected as spatial changes in relative spectral line intensity of reflections of laser light over broad area by new techniques described herein using techniques and equipment similar to those previously disclosed in U.S. Pat. No. 4,862,257 and assigned to the assignee hereof.
In view of the foregoing, there continues to be a need for an accurate and efficient method and apparatus for the remote measuring of anomalies (such as internal waves) which are present below the surface of a body of water, particularly below the thermocline of the ocean.